184 CYPERACEAE 
perianth-bristles overtopping the body of the achene: achenes broadly obovoid, fully 1 mm. 
long ; tubercle about $ as high as the body of the achene. 
In moist soil, Arkansas to Texas. Summer and fall. 
17. Bleocharis nodulósa (Roth) Schult. Perennial by horizontal rootstocks. Scapes 
closely tufted, relatively stout, 3-10 dm. tall, copiously nodose-septate, invested at the base 
by more or less discolored sheaths, constricted below the summit: spikelet conic-cylindric, 
acute, 1-2 cm. long, 4-6 mm. thick : scales closely imbricated, oblong-lanceolate, often con- 
stricted below the apex, 3-4 mm. long, scarious-margined : perianth-bristles very variable 
in length: achenes obovoid, pinched at the base, about 1 mm. long, plump ; tubercle 
deltoid, about 4 the width of the body of the achene. 
In swamps, Florida to Louisiana and Arizona. Also in tropical America. Spring to fall. 
18. Eleocharis macrostachya Britton. Perennial by relatively short rootstocks, 
pale green or straw-colored. Scapes tufted, 2.5-12 dm. long, stout: spikelet narrowly 
cylindric or linear-lanceolate in outline, 1-2.5 em. long, many-flowered, acute: scales ob- 
long-ovate to lanceolate, often rather acute, pale green or straw-colored with darker ribs : 
perianth-bristles 5-6, as long as the achene or somewhat shorter, retrorsely barbed, or 
sometimes very short: stigmas 2: achenes lenticular, obovoid, about 1.5 mm. long, ex- 
cluding the small cap-like tubercle, lemon-yellow. 
In low grounds, Arkansas to Nevada, Louisiana, Texas and Arizona. Spring to fall. 
19. Bleocharis glaucéscens ( Willd.) Schult. Perennial by horizontal rootstocks. 
Scapes tufted, slender, 1-9 dm. long, bright or deep green : spikelet oblong or oblong-lan- 
ceolate, 0.5-1.5 em. long, acute or rather obtuse: scales brown or dark green, blunt or 
acute in age: perianth-bristles usually 4, about as long as the achene or shorter or nearly 
wanting: stigmas 2: achenes lenticular, obovoid, about 1.5 mm. long, excluding the nar- 
row conic tubercle, brown. 
In swamps or meadows, Ontario to Minnesota, Nebraska, Florida and Texas. Spring to fall. 
20. Eleocharis Ravenélii Britton. Perennial, bright green. Scapes tufted, 3-5 
dm. long, slender: spikelet lanceolate or oblong-lanceolate in outline, 8-11 mm. long, 
acute: scales oblong to oblong-lanceolate, rather blunt, scarious-margined, brown on either 
side of the prominent midrib: perianth-bristles 4-5, somewhat shorter than the achene: 
stigmas 2: achenes biconvex, plump, 1 mm. long or less, narrowly obovoid, somewhat con- 
stricted at the top, smooth or nearly so ; tubercle depressed. 
In sandy soil, southern Texas. Spring. 
21. Eleocharis acicularis ( L.) R. & S. Perennial by filiform stolons or rootstocks. 
Scapes tufted, finely filiform or setaceous, obscurely 4-angled and grooved, weak, erect or 
reclining, 5-20 em. long: sheaths truncate: spikelet compressed, narrowly ovate or linear- 
oblong, acute, broader than the scape, 3-10-flowered, 3-10 mm. long, 1 mm. wide: scales 
oblong, obtuse, or the upper subacute, thin, pale green, usually with a narrow brown band 
on each side of the midvein, deciduous, many of them commonly sterile : perianth-bristles 
3-4, fragile, fugacious, shorter than the achene: stigmas 3: achenes obovoid-oblong, 0.5 
mm. long, pale, obscurely 3-angled with a rib on each angle and 6-9 lower intermediate 
ribs connected by fine ridges; tubercle conic, acute, } as long as the acbene. 
In wet soil, throughout North America, except the extreme north. Also in Europe and Asia. 
Summer and fall.—A variety, E. acicularis radicans Sone Britton, is distinguished by its relatively 
stout scapes and thicker spikelets. Texas, California and Central America. 
22. Eleocharis Chaetaria R. & S. Perennial or annual. Scapes tufted, 2-20 cm. 
long, curved, filiform or wire-like, smooth, barely constricted at the summit, with a green 
sheath at the base: spikelet erect, oblong or ovoid-oblong, 2-3 mm. long, 1-4-flowered, 
flattened : scales in 2 or 3 rows, thin, barely discolored : perianth-bristles 6, about as long 
as the achene, sometimes much reduced : stigmas 3: achenes 3-angled, obovoid, barely 1 
mm. Jong ; tubercle pyramidal, shorter than the body of the achene. 
In sandy soil or low grounds, southern Alabama. Alsoin the West Indies and most tropical and 
warm-temperate regions. Spring to fall. 
23. Eleocharis vivipara Kunth. Perennial by horizontal rootstocks, pale green. 
Scapes very numerous, tufted, very slender, 1-3 dm. long, not rigid, sometimes spreading, 
barely constricted at the summit: spikelet linear-oblong, 4-7 mm. long, acutish, often 
sparingly proliferous : scales oblong or ovate-oblong, blunt, scarious-margined, closely im- 
bricated, somewhat discolored : perianth-bristles 6, barbed, unequal in length : achenes ob- 
ovoid, nearly white, 3-angled, plump, about 1 mm. long, finely cancellate ; tubercle deltoid, 
or depressed, shorter than the body of the achene. 
In low grounds and on shores, South Carolina to Florida and Texas. Summer and fall. 
21. Eleocharis tórtilis (Link) Schult. Annual. Scapes tufted, filiform, sharply 3- 
angled, pale green, erect or reclining, twisting when old, 3-4 dm. long : sheaths obliquely 
truncate, 1-toothed : spikelet ovoid or oblong, rather acute, several-flowered, 4-6 mul 
about 2 mm. thick, much thicker than the scape: scales firm, pale, ovate, mostly obtuse : 
